Shield Arms SAS15NCGEN3 S15 Magazine Gen 3 15rd Flush 9mm Luger Fits Glock 48/43X Black Steel
https://www.tandktactical.com/shop/850029544999-shield-arms-sas15ncgen3-s15-magazine-gen-3-15rd-flush-9mm-luger-fits-glock-48-43x-black-steel-36132
https://www.tandktactical.com/web/image/product.template/36132/image_1920?unique=98007ff
The S15 is a steel magazine, and is the same length as the OEM Glock 10 round magazine, but holds an additional 5 rounds.